As you know, the ionic strength of each buffer is different than other buffers. For example, acetate buffer has ionic strength different than phosphate buffer, even they have same concentration (M or mM).
When i calculate the ionic strength for such a buffer, it gives me for example 0.005 M. Therefore, NaCl or KCl should be prepared at the same ionic strength to the buffer (0.005), In order to get as a total 0.01.
My question is how I know the certain volume to be added to the buffer to make up to 0.01, is there any equation i could use to calculate how much?
If you see the ionic strength equation, the volume is not taken into the account.
Please could you help
what kind of the buffer solution do you have? Its composition is of considerable importance to estimate I.
Besdes, I'm personally interested in your way of the ionic strength calculation of your buffer solution.
Many thanks all,
But my question, How can i calculate the ionic strength at certain pH, for example phosphate buffer can be prepared at pH 6-8, and at each pH the ionic strength should be different.
Christian, Could you please tell how you know the appropriate amount of salt you add?
For example if the ionic strength of phosphate buffer 0.005 M, and need to make it to 0.01, I should prepare 0.005 M of salt. Therefore, i should calculate how many g of salt for concentration 0.005, then i should add the quantity of salt in g to dissolve it in phosphate buffer to be 0.01. Am I right?
Please see the attachment. It shows preparation of wide range of pH using different buffer. But most thing confused me how can i know that add HCl or NaOH would change the ionic strength?
Use this on-line calculator where you can change anything you need:
http://www.biomol.net/en/tools/buffercalculator.htm
Many thanks Michael,
That really helps, but i would like to know how it is done!!
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